U.S. patent application number 12/496134 was filed with the patent office on 2010-01-07 for pump with cutting impeller and pre-cutter.
This patent application is currently assigned to BRINKMANN PUMPEN K.H. BRINKMANN GMBH & CO. KG. Invention is credited to Peter Wagner, Dirk Wenderott.
Application Number | 20100003124 12/496134 |
Document ID | / |
Family ID | 41464525 |
Filed Date | 2010-01-07 |
United States Patent
Application |
20100003124 |
Kind Code |
A1 |
Wagner; Peter ; et
al. |
January 7, 2010 |
Pump with Cutting Impeller and Pre-Cutter
Abstract
A pump includes a cutting impeller (38) and a pre-chopper (50)
driven by a shaft portion (46) that projects axially from the
cutting impeller (38), with the pre-chopper (50) being surrounded
by an intake port (22) of the pump, the intake port having, at
least on a part of its length, in the vicinity of the pre-chopper,
a non-circular internal cross-section.
Inventors: |
Wagner; Peter; (Werdohl,
DE) ; Wenderott; Dirk; (Castrop-Rauxel, DE) |
Correspondence
Address: |
Richard M. Goldberg, Esq;Suite 419
25 East Salem Street,
Hackensack
NJ
07601
US
|
Assignee: |
BRINKMANN PUMPEN K.H. BRINKMANN
GMBH & CO. KG
Werdohl
DE
|
Family ID: |
41464525 |
Appl. No.: |
12/496134 |
Filed: |
July 1, 2009 |
Current U.S.
Class: |
415/121.1 |
Current CPC
Class: |
F04D 7/045 20130101;
B02C 2018/164 20130101; F04D 29/2288 20130101 |
Class at
Publication: |
415/121.1 |
International
Class: |
F04D 29/18 20060101
F04D029/18 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 5, 2008 |
DE |
10 2008 031 842.6 |
Claims
1. A pump comprising: a cutting impeller, a pre-chopper, a shaft
portion that drives the pre-chopper and cutting impeller and that
projects axially from the cutting impeller, and an intake port that
surrounds the pre-chopper, said intake port having, at least on a
part of its length, in the vicinity of the pre-chopper, a
non-circular internal cross-section.
2. The pump according to claim 1, wherein the pre-chopper has two
blades which, together, form the shape of an "S" and are curved
such that a convexly curved side thereof is ahead in a direction of
rotation of the pre-chopper.
3. The pump according to claim 2, wherein distal ends of the blades
are angled away from a plane of the pre-chopper.
4. The pump according to claim 1, wherein the prechopper has at
least one axially projecting lug that is arranged
eccentrically.
5. The pump according to claim 1, wherein the intake port includes
an internal wall formed, approximately level with the pre-chopper,
with four pockets which have approximately the shape of square
truncated pyramids and give the intake port an approximately square
internal cross-section.
Description
[0001] The invention relates to a pump having a cutting impeller
and a pre-cutter driven by a shaft portion that axially projects
from the cutting impeller.
[0002] A pump of this type is known from DE 10 2005 014 348 B3 and
is used for example in machine tools for circulating lubricating
coolant emulsions that are contaminated with metal chippings. This
pump is a centrifugal pump that is additionally provided with an
axial impeller disposed upstream of a radial impeller, said axial
impeller being configured as a cutting impeller and having, at its
upstream end, cutting edges that cooperate with stationary counter
blades arranged radially in a suction passage, so that chippings
and other contaminants that have been sucked in are cut-off and
chopped. The pre-cutter serves for chopping coarse contaminants
before they are sucked-in by the axial impeller and are then
chopped further.
[0003] It is an object of the invention to provide a pump of the
type indicated above, wherein the chopping properties are further
improved. According to the invention, this object is achieved by
the feature that the pre-chopper is surrounded by an intake port of
the pump, which intake port has, at least on a part of its length
close to the pre-chopper, a non-circular internal
cross-section.
[0004] The chippings that are produced in machine tools typically
have a helical shape and have a tendency to cling together an to
form relatively complex clews which are difficult to be sucked-in
and chopped. The pre-chopper of the pump has the task, to resolve
these clews or at least to loosen them to such an extent that the
chippings are transported into the range of the cutting impeller
and can be chopped there. It has turned out that the features
according to the invention provide a significant improvement in the
efficiency of the prechopper.
[0005] At first, the surrounding intake port is effective to
concentrate the current and thereby to ensure that the clews of
chippings are drawn into the range of the pre-chopper more
efficiently.
[0006] The rotating pre-chopper induces a rotation of the chipping
clews, so that the latter move circumferentially along the internal
wall of the intake port. Since this wall has a non-circular
cross-section, the passageway for the chippings revolving between
the pre-chopper and the internal wall of the intake port becomes
broader and narrower in an alternating way. It has been shown that
this is very favorable for resolving the chipping clews which can
then readily be conveyed towards the cutting impeller and can
finally be chopped there.
[0007] Moreover, the intake port forms a protector against
accidental contact, which permits to install the pump in a
lubricating coolant reservoir in a position, e.g. horizontally, in
which the intake portion is accessible for the personnel.
[0008] Useful embodiments and further developments of the invention
are indicated in the dependent claims.
[0009] Preferably, the pre-chopper has the shape of a blade wheel
with lugs projecting in axial direction, which lugs cause a strong
swirl in the liquid that is being sucked-in and thus have the
effect that the chipping clews revolve concurrently with the
pre-chopper and move relative to the wall of the intake port with
high velocity.
[0010] An embodiment example will now be described in conjunction
with the drawings, wherein:
[0011] FIG. 1 is an axial cross-sectional view of a pump according
to the invention;
[0012] FIG. 2 is a perspective view of an intake portion of the
pump;
[0013] FIGS. 3-5 show different views of a pre-chopper; and
[0014] FIG. 6 is a cross-sectional view taken along the line VI-VI
in FIG. 1.
[0015] The centrifugal pump shown in FIG. 1 has an essentially
cylindrical casing with a head member 12 flanged to the lower end
of the casing, and at least this head member 12 is immersed in a
liquid reservoir (not shown) in a machine base of a machine tool. A
pump chamber 14 accommodating a radial impeller 16 is formed inside
of the head member 12. A shaft 18 is coaxially supported in the
casing 10, and a top end thereof is connected to a drive motor (not
shown) and is supported in stationary bearings that have not been
shown. These bearings determine the axial position of the shaft 18.
The radial impeller 16 is keyed onto the shaft 18. A wall of the
head member 12, which wall forms the lower part of the pump chamber
14, is formed with a suction passage 20 projecting downwardly
coaxially with the impeller 16 and the shaft 18, and an intake port
22 is axially adjoined thereto.
[0016] The impeller is a semi-open impeller equipped with blades 24
that are open downwardly. These blades are inclined in such a
manner that the liquid is sucked-in via the intake port 22 and the
suction passage 20 and is then conveyed radially outwardly into an
annular chamber 26 above the outer periphery of the pump chamber
14. As a result of the liquid pressure that is built up in the
annular chamber 26 in this way, the liquid flows upwardly in
direction of an arrow A through a rise passage 28 formed in the
casing 10 towards a pump outlet port 30 that has not been shown in
FIG. 1 (FIG. 6).
[0017] An intake plate 32 is arranged at the lower end of the
suction passage 20, said intake plate defining the bottom of the
pump chamber 24 and having an intake opening 34 (FIG. 2).
[0018] A cutting impeller 38 configured as an axial impeller and
equipped with helical blades 36 is mounted on the shaft 18 inside
of the suction passage 20. The cutting impeller 38 conveys the
liquid from the top end of the intake port 22 axially upwardly
through the intake opening 34 into the interior of the pump chamber
14.
[0019] FIG. 2 shows the pump in a bottom view. Looking through the
intake opening 34, one can see the blades 36 of the cutting
impeller. The intake plate 32 forms two counter blades 40
projecting radially inwardly into the intake opening 34 and having
cutting edges 42 that co-operate with toothed cutting edges 44 of
the blades 36. The counter blades 40 are curved in a spiral shape,
thereby deviating from the radial direction towards the direction
of rotation of the impeller (in counterclock direction in FIG. 2)
when passing from the inside to the outside.
[0020] Since the cutting edges 44 of the cutting impeller extend in
essentially radial direction, whereas the cutting edges 42 of the
counter blades have a spiral shape, the cutting edges cooperate
like scissors when the cutting impeller rotates. When the cutting
edges meet each other, the scissors action proceeds essentially
radially from the inside to the outside. In the outer part,
however, the cutting edges 44 are curved in a direction opposite to
the running direction of the cutting impeller 38.
[0021] The cutting edges 44 project radially outwardly beyond the
radius of the intake opening 34, and the cutting edges 42 extend
inwardly into the hub portion of the cutting impeller. Thus, each
pair of cutting edges defines a window that becomes closed
completely during a cutting action. In this way, chippings and
other contaminants are chopped reliably.
[0022] In the range of the cutting edges, the blades 36 and the
counter blades 40 are for example made of hardened steel having a
Rockwell hardness of 60 HRC. The hardness and the axial distance
between the cutting edges 42 and 44 has to be determined in
accordance with the intended use of the pump. It is also possible
that, in operation, the cutting surface of the cutting impeller
slides on the intake plate 32. The axial distance between the
cutting edges 42, 44 can be changed and adjusted by means of spacer
sheets. For example, the spacer sheets are inserted from outside
between the intake plate 32 and the head member 12, so that the
distance between the intake plate and the cutting edges 44 is
changed.
[0023] The toothed configuration of the cutting edges 44 of the
blades 36 assures that chippings, if present, are caught and
entrained by the teeth of the cutting edge, are held during the
cutting operation and are then separated. This prevents the
chippings from moving radially outwardly along the cutting edge 42.
The teeth of the cutting edge 44 may have such a shape that each of
them is oriented at right angles to the corresponding portion of
the curved cutting edge 42 of the counter blade (not shown).
[0024] As an alternative or in addition, teeth may also be provided
on the cutting edges 42 of the counter blades 40.
[0025] As can be seen in FIG. 1, the lower end of the shaft 18 is
prolonged by a thinner shaft portion 46 that projects downwardly
beyond the cutting impeller 38 into the intake port 22 and carries,
at its lower end, a pre-chopper 50 equipped with two blades 48. In
FIG. 1 the plane of the cross-section passes through one of the
curved blades 48, so that the latter appears to be separated from
the main part of the pre-chopper.
[0026] The pre-chopper 50 has been shown in greater detail in FIGS.
3 to 5. FIG. 3 shows the pre-chopper in an axial view. It can be
seen that the blades 48, together, form the shape of an "S". As can
be seen more clearly in FIGS. 4 and 5, the distal ends 52 of the
blades are however angled away from the plane of the pre-chopper,
such that the blades assist in the transport of the liquid medium
towards the suction passage 20 like propellers. Moreover, the
pre-chopper has, in the vicinity of its hub, two lugs 54 that
project axially towards the mouth of the intake port 22.
[0027] This shape of the pre-chopper 50 has the effect that clews
of chippings that are entrained in the liquid that is being
sucked-in, are swirled efficiently, so that they rotate at high
speed together with the pre-chopper and, consequently, move along
the internal wall of the intake passage 20 in circumferential
direction until they have finally passed the pre-chopper and enter
into the suction passage 20 through the intake opening 34, where
they are chopped further.
[0028] The shape of the internal wall of the intake port 22 has
been illustrated in FIGS. 1, 2 and 6. While the internal
cross-section of the intake port generally tapers in a funnel shape
from a mouth 56 at the lower end in FIG. 1 towards the intake end
of the suction passage 20, for pockets 58 are formed in the
peripheral wall and distributed circumferentially with equal
angular spacings, in a position approximately level with the
pre-chopper 50 but slightly offset from the latter towards the
outside, each of said pockets having the shape of a shallow,
rounded-off pyramid.
[0029] As can be seen in the cross-sectional view in FIG. 6, this
has the effect that, here, the intake port 22 has a non-circular,
approximately square internal cross-section. As a result, the
chipping clews that have been caused to revolve rapidly by the
pre-chopper 50 are "crunched" at the internal wall of the intake
port 22 and are resolved in this way before they reach the cutting
impeller 38. Thus, the intake port serves as a stationary support
which, together with the rotating pre-chopper, loosens and resolves
the clews of chippings. Moreover, the intake port 22 serves as a
protector that prevents that a person reaching with his or her hand
into the intake range of the pump is hurt by the rotating
pre-chopper. This permits to install the pump also in a horizontal
posture, for example, as has been shown in FIG. 6.
* * * * *